Quartz 4

Unit Self-Test

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Level IV Clinical Treatment — Unit D Self-Test

Module 1: Interaction with Orthodontists

Question 1

Which of the following are reasons that a relatively higher percentage of orthodontic treatment is done in specialty practice?

a. Early development of specialty

b. Less emphasis in dental school

c. Efficiency in practice relative to instruments/materials

d. Positive social interaction

  1. a and b
  2. b and c
  3. a, b, and c ✓
  4. b, c, and d
  5. all of the above

Correct

That’s right, three of these possibilities affect the number of patients referred to specialty practice: the early development of orthodontics as a specialty due to Edward Angle’s influence, less orthodontic clinical experience in dental school, and efficiency relative to supplies and materials. Social interaction has little or nothing to do with it.

Question 2

Which is the most important reason that an obvious jaw asymmetry in a child is a reason for early referral?

  1. The asymmetry may be due to a congenital anomaly.
  2. The asymmetry is likely to be due to a condylar fracture or injury.
  3. The asymmetry can be a progressive deformity that steadily gets worse. ✓
  4. Growth modification is the probable treatment.
  5. The child may need surgery to create the possibility of future growth.

Correct

That’s right, all these statements are correct, but the most important reason for early referral is the possibility that the asymmetry is a progressive deformity, one that gets steadily worse as the affected area does not grow and other normal areas do. Early evaluation is important, and early surgery may be needed.

Question 3

In the analysis of facial proportions, the “rule of thirds” means that

  1. one-third of children have disproportions in facial dimensions.
  2. one-third of children have normal proportions.
  3. nasal height equals the thirds of the face above and below the nose. ✓
  4. the lower third of the face should be longer than the areas above.
  5. the upper third of the face can be ignored when orthodontics is planned.

Correct

That’s right, nasal height constitutes the middle third of the face, and it should be the same size as the upper third (hairline to bridge of nose) and lower third (base of nose to chin). All the other possible answers are simply wrong.

Question 4

Triage is the process of

  1. breaking the life span into three sections.
  2. sorting patients by problem severity. ✓
  3. determining which patients should be referred immediately.
  4. determining which patients eventually will need referral.
  5. all of the above

Correct

That’s right, triage is the process of sorting patients by problem severity. In its military application, it is used to sort casualties after battles so that those who would most benefit from prompt treatment are treated first. Similar thinking determines which children would be referred for more complete evaluation at an early age.

Question 5

The major reason for referral of children with a craniofacial syndrome to a craniofacial team is

  1. correct syndrome diagnosis allows prediction of future growth. ✓
  2. behavior management is likely to be a particular problem with these children.
  3. early treatment often is needed.
  4. the probability of early jaw surgery is high.
  5. parents of such children can be particularly demanding and difficult.

Correct

That’s right, it’s important to obtain a correct syndrome diagnosis as early as possible, because this allows much better prediction of future growth and development and therefore is an important guide to treatment planning. Whether the other statements are true depends on the individual case. They aren’t true for all (or even the majority) of children with craniofacial syndromes.

Question 6

What of these is the major reason for referral of a child with obvious protrusion of the incisors on profile examination?

  1. Cephalometric analysis and monitoring are needed. ✓
  2. Extraction of teeth and space closure probably is required.
  3. Opening the midpalatal suture may be necessary.
  4. Treatment probably will take more than 2 years.
  5. If protrusion is obvious, there’s no need for referral.

Correct

That’s right, the major reason in this list for referral of a child with obvious protrusion of the incisors is that cephalometric analysis is needed to plan tooth movement for children of this type. Cephalometric analysis also can help determine the best time for treatment, may allow a comparison of the probable outcomes of alternative treatment possibilities, and is required for monitoring the progress of treatment.

Question 7

(A) A supernumerary tooth observed on the panoramic radiograph of a child always is a severe problem indicating referral because (B) These teeth may damage other developing teeth or produce asymmetries in the dental arch.

  1. A true, B true, A and B related
  2. A true, B true, A and B not related
  3. A true, B false
  4. A false, B true ✓
  5. A and B false

Correct

That’s correct. The first statement is false, but the second one is true. Multiple supernumeraries constitute a severe problem, but a single uncomplicated supernumerary, in the absence of skeletal problems, can just be extracted. By itself, it is not an indication for orthodontic referral.

Question 8

Which of the following best describes the role of space analysis in determining the need for orthodontic referral?

  1. The bigger the discrepancy, the greater the chance referral is indicated. ✓
  2. Refer children with >4 mm discrepancy.
  3. Refer children with excess spacing.
  4. Refer children with space discrepancy due to early loss of primary teeth.
  5. All of the above are correct.

Correct

That’s right, there are no hard-and-fast rules about the magnitude of space discrepancy and the need for referral, but in general, the bigger the discrepancy, the greater the chance that referral is indicated. Whether children with >4 mm discrepancy, excess spacing or a discrepancy due to early loss of primary teeth are treated in family practice is very much up to the family dentist’s interest and competence.

Question 9

For a girl with Class II malocclusion and obvious mandibular deficiency, what’s the best time for treatment?

  1. Before the adolescent growth spurt
  2. During the adolescent growth spurt ✓
  3. Before the end of the mixed dentition
  4. Not until the permanent second molars are near eruption
  5. Treatment should coincide with eruption of the maxillary canines

Correct

That’s right. The best time for treatment of most patients with Class II malocclusion is during the adolescent growth spurt, although some children may benefit from earlier treatment. It’s important to plan the timing of referral based on physical development, not dental development. Some girls are well into their growth spurt before canines, premolars, or second molars begin to erupt and need to have treatment started in the mixed dentition. For referral timing, look at secondary sexual characteristics, not the teeth.

Question 10

Which of the following are indications for early (preadolescent) referral of a girl with Class II malocclusion?

a. Psychologic difficulties related to teasing

b. Trauma to soft tissues from the occlusion

c. Exceptionally severe skeletal discrepancy

d. Anterior open bite combined with the Class II problem

  1. a and b
  2. b and c
  3. a, b, and c
  4. b, c, and d
  5. all of the above ✓

Correct

That’s right, all of these are indications for early (preadolescent) referral. Starting treatment prior to adolescence usually means that two phases of treatment will be required, so special indications for treatment should be present before early treatment is recommended.

Question 11

Which of the following is the most important indication for early (preadolescent) referral?

  1. Deep bite Class II
  2. Open bite Class II
  3. Crowding > 10 mm
  4. Maxillary deficient Class III ✓
  5. Mandibular prognathic Class III

Correct

That’s right, a Class III problem due maxillary deficiency is particularly important for early referral, because the window of opportunity for growth modification in these children closes at age 8 or 9. Waiting for adolescence to refer them will mean that effective growth modification cannot be achieved.

Question 12

Which of the following should you expect in a report from the orthodontist after you have referred a child for evaluation?

a. Diagnostic problem list from the evaluation

b. Treatment recommendations

c. Copies of radiographs

d. Digital photographs

  1. a, b, and c
  2. b, c, and d
  3. a, c, and d
  4. all of the above ✓

Correct

That’s right, you should expect a diagnostic problem list, treatment recommendations and copies of radiographs that would be useful in your dental practice (which may or may not include cephalometric radiographs, depending on your preference). Unless you have told the orthodontist you don’t want them, you also are very likely to get prints of digital photographs that you can add to your chart.

Question 13

What is the ideal time for the beginning of orthodontic treatment after you have extracted teeth at the orthodontist’s request?

  1. Within 10 days
  2. 2-6 weeks postextraction ✓
  3. 6-12 weeks postextraction
  4. Not until at least 3 months have passed
  5. Doesn’t matter if within the first year

Correct

That’s right, orthodontic space closure should start between 2 and 6 weeks after the extractions. Waiting longer increases the chance of bone resorption at the extraction site that can complicate the space closure and result in alveolar defects long term.

Question 14

If restorations are planned after the orthodontics is completed, how is this treatment coordinated with the orthodontic retainers?

  1. Retainer immediately after debond, new one immediately after restorations ✓
  2. Restorations immediately after debond, retainer immediately after restorations
  3. Retainer immediately after debond, restorations are permanent retainer
  4. Retainer immediately after debond, new retainer if needed 3 months after restorations
  5. Retainer doesn’t matter within the first year, make one after restorations if needed

Correct

That’s right, when restorations are planned, a retainer should be placed immediately after the orthodontic appliance is removed (unless the restorations are to be done with a day or so), and as soon as the restorations are completed, an impression for a new retainer should be made. The original retainer won’t fit after the restorations are done, and even if no further retention is needed in the area where the restorations are placed (around a bridge for example), a modified retainer to maintain other relationships almost surely will be required.

Module 3: Accelerated Tooth Movement

Question 1

Which of the following would not be an acceptable way to speed up orthodontic tooth movement?

  1. more flexible archwires
  2. shorter intervals between appointments ✓
  3. better orthodontic brackets
  4. NiTi auxiliary springs
  5. all of these would be OK

Correct

That’s right, shorter intervals between appointments is not an acceptable way to speed up tooth movement. If force is heavy and interrupted, this would not allow time for repair of damaged areas of bone and tooth roots; if force is continuous, more frequent appointments would have little effect because movement was continuing anyway. But remember that heavy continuous force would maximize damage to tooth roots, so it’s not acceptable.

Question 2

What is the first thing that happens when an orthodontic spring is activated against a tooth?

  1. bending of alveolar bone ✓
  2. displacement of the tooth in the PDL space
  3. release of chemical agents from affected cells
  4. interruption of blood flow to compressed areas
  5. all of them happen simultaneously

Correct

That’s right, the first thing to occur when force of any magnitude is placed against a tooth is bending of the alveolar bone. The tooth moves relative to external landmarks, but not within the PDL space until fluid is squeezed out as the bone springs back and the tooth is held where the spring pushed it. So answers 1 and 2 occur in that order; items 3 and 4 do occur essentially simultaneously.

Question 3

How long does it take for pain from heavy force against a tooth to develop?

  1. a few seconds ✓
  2. a few minutes
  3. a few hours
  4. about 24 hours
  5. a few days

Correct

That’s right, heavy force causes pain almost immediately, after just a few seconds. It develops as the bone springs back after teeth are displaced. That’s why you don’t maintain heavy force as you eat your dinner—you bite down and then remove the force, maintaining the pressure for only a few seconds. It’s also one of the ways you can tell if too much force is being delivered by an orthodontic wire or spring—if it hurts immediately as the wire is tied into a bracket or when the spring is connected, the force is too great.

Question 4

How long does it take for piezo-electric signals to disappear after an orthodontic archwire is activated?

  1. a few seconds ✓
  2. a few minutes
  3. a few hours
  4. about 24 hours
  5. a few days

Correct

That’s right. There would be a piezo-electric signal as the bone bends and when it bends back—and no further piezo-electric activity caused by the archwire, which would hold the tooth in position but would not cause further bone bending. So from a piezo-electric perspective, the action would be over in a few seconds—and that fits with what we know, that tooth movement has little or nothing to do with pizeo-electricity.

Question 5

With orthodontic force heavy enough to produce significantly large areas of necrosis in the periodontal ligament, how long does it take to get tooth movement?

  1. a few hours
  2. about 24 hours
  3. about 2 days
  4. 3-5 days
  5. about 10 days ✓

Correct

That’s right, it would take about 10 days. Undermining resorption would be required because in the necrotic areas there would be no cells left to differentiate into osteoclasts and osteoblasts. Penetration of cells from adjacent PDL areas is slow, and activation of cells in the bone marrow beneath the lamina dura is necessary. It takes a few days for chemical signals to reach the bone marrow, and it takes another few days for the newly-formed osteoclasts in the bone marrow to remove the bone beneath the necrotic PDL area.

Question 6

(A) Heavy orthodontic force causes pain because (B) heavy force causes greater stress on anchor teeth and more movement of anchor teeth. These statements are:

  1. A true, B true, related
  2. A true, B true, not related ✓
  3. A true, B false
  4. A false, B true
  5. A and B false

Correct

That’s correct. A and B are true, but they have no cause and effect relationship. Heavy orthodontic force causes pain because of the necrotic areas and inflammation in the PDL that it produces. More movement of anchor teeth has to do with the differential in pressure between anchor teeth and those you want to move, whether or not pain is produced. So there’s no cause and effect relationship between the two true statements—except that both pain and loss of anchorage are undesirable effects of heavy force.

Question 7

Which of the following statements correctly describe magnets as orthodontic springs?

  1. they produce more blood flow through the PDL
  2. they exert particularly heavy force as they come closer together
  3. piezo-electric signals are magnified by the presence of an electro-magnetic field
  4. protecting against corrosion is a critical part of magnet design
  5. a and b
  6. a and c
  7. b and c
  8. b and d ✓
  9. c and d

Correct

That’s right, the non-linear forces produced by magnets are a correct description, and so is the need to protect patients from potentially dangerous corrosion products if magnets are used intra-orally. They don’t change the biology, so they don’t affect blood flow and piezo-electric signals. Those characteristics indicate why magnets are not used much in modern orthodontics even though they can serve as orthodontic springs—they have poor spring characteristics, are potentially dangerous, and don’t affect the biologic response favorably (or unfavorably).

Question 8

Which of the following drugs would be most likely to speed up tooth movement?

  1. prostaglandin E ✓
  2. Relaxin
  3. ibuprofen
  4. acetaminophen
  5. Fosamax

Correct

That’s right, prostaglandin E stimulates both osteoclastic and osteoblastic activity, so it should speed up tooth movement and there is some evidence that it does—at the price of significant pain. Relaxin was not effective in a clinical trial; ibuprofen and Fosamax (a widely used bisphosphonate) can slow down tooth movement, and acetaminophen doesn’t affect it.

Question 9

Which of the following are correct about orthodontic treatments for patients who are taking a bisphosphonate for control of osteoporosis?

  1. there is about a 3 month delay in tooth movement after a bisphosphonate is discontinued
  2. extraction of teeth in orthodontics for a bisphosphonate patient is more likely to be necessary
  3. temporary replacement of the bisphosphonate with Evista may facilitate treatment
  4. heavier than normal orthodontic force is likely to be needed
  5. a and b
  6. a and c ✓
  7. b and c
  8. b and d
  9. a, c and d

Correct

Yes, that’s right, there is about a 3 month delay, and replacing the bisphosphonate with Evista can maintain osteoporosis control during orthodontic treatment. Extractions in a bisphosphonate patient are not a good idea because of the possibility of severe bone healing problems, and heavier orthodontic force would not increase the rate of bone remodeling that is necessary for tooth movement.

Question 10

Which of the following are disadvantages of 21st century corticotomy?

  1. large gingival flaps
  2. green-stick fractures of alveolar bone
  3. major blood loss
  4. long delay before initiating orthodontic treatment
  5. a only ✓
  6. b only
  7. a and b
  8. b and d
  9. a, c and d

Correct

That’s correct. The large gingival flaps are a disadvantage because of the extensive surgery to elevate and reposition them, which increases morbidity compared to less invasive approaches. Green-stick fractures of alveolar bone are not part of current corticotomy techniques, and neither major blood loss nor a long delay in initiating orthodontic treatment would be expected.

Question 11

Which of the following are potential advantages of the bone graft slurry used with corticotomy and piezocision?

  1. prevention of loss of alveolar bone height
  2. prevention of dehiscences in alveolar bone with orthodontic expansion
  3. faster healing of the bone cuts
  4. reduction in post-operative pain
  5. a only
  6. b only
  7. a and b ✓
  8. b and d
  9. a, c and d

Correct

That’s right, the bone grafts are said by proponents of corticotomy and piezocision to prevent loss of alveolar bone height, and to decrease the possibility of bone dehiscence (breaks in the continuity of bone over the tooth roots) with subsequent orthodontic arch expansion. They aren’t used to increase the rate of healing of the bone cuts (which they would not be expected to affect) and have no effect on post-operative pain. The extent to which either of the potential advantages are real advantages has not been determined by evidence-based studies, and that must be kept in mind when evaluating these treatment procedures.

Question 12

How much time in treatment should you expect to save with bone injury techniques during typical orthodontic therapy?

  1. 2-3 months ✓
  2. up to 6 months
  3. 33% reduction in treatment time
  4. 50% reduction in treatment time
  5. 75% reduction in treatment time

Correct

That’s correct. Two months is the best answer in the above list—although there are no good data to support any of these answers. The effect of bone injury wears off in about 4 months, and if you moved the teeth twice as fast during that time, you would save about 2 months. There is no reason to expect that more rapid bone remodeling would occur after repair is complete, and no data to support that contention.

Question 13

What is the mechanism of action for high-energy vibration to make teeth move faster?

  1. activation of osteoclasts
  2. increase in blood flow to the PDL
  3. repair of micro-fractures in the alveolar bone
  4. increased release of cytokines and prostaglandin in the PDL
  5. the mechanism is unknown ✓

Correct

That’s right, the mechanism by which vibrating the teeth increases the rate of tooth movement (if it does) is unknown. That’s a problem because it is difficult to know what side effects and potential problems to look for without a firm biologic rationale. That is important when you are evaluating the claims from proponents for any new methodology. You have to look very carefully at the supporting data when the mechanism is really unknown.

Question 14

(A) The most likely mechanism by which high-intensity light accelerates tooth movement (if it does) is increased blood flow because (B) light chills the tissues it affects and cold is known to facilitate healing. These statements are:

  1. A true, B true, related
  2. A true, B true, not related
  3. A true, B false ✓
  4. A false, B true
  5. A and B false

Correct

That’s right, A is true and B is false. Light energy is known to heat tissues, heating tissues is known to increase blood flow, and increased blood flow seems to facilitate tooth movement, so A is the most likely mechanism at present—though the mechanism is not understood.. Even though correctly-timed cold can facilitate healing after injury, light doesn’t chill tissues, so B is incorrect. What is the real mechanism for tissue-penetrating light? That’s still unknown.

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